1. Field of Invention
The present invention relates to devices and methods for forming thin films by applying a coating solution containing a film-forming material dissolved or dispersed in a solvent onto a substrate, to liquid crystal displays and devices and methods for manufacturing the same by using the devices and methods described above, to thin film structures and devices and methods for manufacturing the same, and to electronic apparatuses. In more particular, the present invention relates to a device and a method capable of forming a thin film having a uniform thickness.
2. Description of Related Art
Currently, as techniques for forming thin films, for example, a spin coating method, which is one of thin-film coating methods, has been generally used. This spin coating method is a method for forming a thin film by dripping a coating solution onto a substrate and subsequently applying the coating solution over the entire substrate using a centrifugal force generated by rotating the substrate. In this coating method, the film thickness is controlled, for example, by a rotation speed and rotation time, or viscosity of the coating solution. This spin coating method has been widely used, for example, for the formation of photoresist films or interlayer insulating films such as SOG (spin on glass) in a semiconductor manufacturing process or the like; the formation of overcoating films (planarization films) or alignment films in a process for manufacturing liquid crystal displays or the like. Further the method has been used in the formation of protection films in a process for manufacturing optical discs or the like.
However, in this spin coating method, since most of the coating solution thus supplied is scattered, a large quantity of the coating solution must be supplied, and at the same time, the waste thereof is large, resulting in disadvantageous increase in cost. In addition, since the substrate is rotated, the coating solution flows from the inside to the outside due to a centrifugal force, and as a result, the thickness at the peripheral region tends to be thick as compared to that at the inside region, resulting in problem of uneven film thickness. As measures against the disadvantages described above, in recent years, a technique using a so-called inkjet method has been proposed.
For example, in Japanese Unexamined Patent Application Publication No. 8-250389, a technique has been disclosed in which a coating solution is applied onto a substrate using an inkjet method to form a thin film. In this technique, a head is relatively and linearly moved with respect to the substrate by a relative moving device so that the coating solution is applied uniformly onto a rectangular substrate.